Induced osteogenesis technology is an usual technology for current surgical repair and periodontal reconstruction, it is mainly to produce new bone by activating bone growth and production function using osteoinductive factor. There are many osteoinductive factors, at present the researches are mainly focused on bone morphogenetic protein (bone morphogenetic protein, BMP) family proteins, the bone morphogenetic protein belongs to low-molecular weight glycoproteins, multiple protein compositions of Bone morphogenetic protein 1 to 14 has been found, wherein the osteoinductive activity of bone morphogenetic protein-2 is strongest, the other bone morphogenetic protein compositions have a synergistic effect with the bone morphogenetic protein-2, participating in the induced osteogenesis process together. Some scholars consider that the bone morphogenetic protein is one of a transforming growth factor-13 (TGF-13) superfamily, it has a marked capability of bone regeneration and osteointegration, it is able to induce formation of cartilage and bone, and it is able to induce transformation of mesenchymal cell around the blood vessel into bone marrow stem cell, the bone morphogenetic protein formed by its interaction with extracellular matrix macromolecule is the basis for adjusting bone formation. The bone morphogenetic protein is widely present in the bone matrix and dental matrix of mammals, it is an acid glycoprotein without species specificity and belongs to local growth factor, but the bone morphogenetic protein in the bone gradually reduces with the age, while reduction of the bone morphogenetic protein in the dental matrix is not seen. Other researches show that the crude extracts of the bone morphogenetic protein in the decalcified bone matrix (DBM) are 10 folds of those in the decalcified dental matrix (DDM) with the same mass, accordingly the induced osteogenesis amount of the decalcified dental matrix in muscle should be 10 folds of that in the decalcified bone matrix with the same mass. But, the bone morphogenetic protein alone diffuses too fast in the body, it is also easy to be broken down by a proteinase, thus it cannot act on more target cells within an effective time, its inductive activity is difficult to be fully achieved; purification and preparation of the bone morphogenetic protein is difficult, and its cost is high, so it is difficult to be widely used in clinical practice; some studies find that the bone morphogenetic protein with high purify cannot obtain high biologically inductive activity, only if being used in combination with the corresponding bone matrix, it can effectively induce osteogenesis, it is because the collagen and the matrix may affect calcium and phosphate ions in hydroxyapatite crystal, the organic substance may also serve as a center for crystallization. Despite there are many reports on carrier for the bone morphogenetic protein, such as using hydroxyapatite, tricalcium phosphate, polyester, collagen, demineralized bone matrix, titanium dioxide, blood clot etc., the binding mode, compounding method, and compounding ratio between the bone morphogenetic protein and the carrier have no consistent conclusion. Therefore, current research direction is transferred to developing a composite osteoinduction material.
Researches consider that the decalcified dental matrix (DDM) is a composite being rich in bone morphogenetic protein, collagen and other proteoglycans, it is a novel bioactive material having an osteoinductive effect with human homology, it is rich in multiple composites of bone inducing protein with its carrier, resulting in a natural slow-delivery system for the bone morphogenetic protein. For example, China Invention Patent 95112416.1, or China Invention Patent Application, Application No. 201310602830.7, Application No. 201310602878.8 disclose that these materials being able to promote wound healing or regeneration of bone are obtained by treatment of tooth. In addition, some compositions may also be added into the dental matrix, to further improve the effect of the dental matrix; for example, such as described in China Invention Patent Application, Application No. 201510089391.3 and Application No. 201110129457.9.
Of courses, there is also a method of in vitro expression of BMP protein then mixed with bone powder or other powder, the actual effect of the repair material prepared by such a method is no ideal, it is mainly because the BMP protein is easy to loss its activity in vitro, it is added into damaged bone after being mixed with these powders, thus it is easy to be degraded by enzymes and also loss its activity. Therefore, only if the activity of BMP is maintained in vivo, growth of the bone tissue can be promoted more effectively.
For the above-described method, despite it has a certain effect on repair of bone damage, there are many inherent defects yet, they are mainly in the flowing aspects: (1) teeth as the source of the active BMP are limited, they cannot meet the growing market demand, because using the dental matrix as the raw material restricts the development of industry; (2) after the tooth and bone are pulverized, they are usually decalcified in a acidic solution, to obtain a powder containing active protein BMP, but treatment by acid and base can release the calcium ion and expose the BMP protein, meanwhile having great damage to BMP protein, it is because BMP is easy to be denaturated in an acidic condition and loss activity; this reduces utilization efficiency of the BMP protein.
Therefore, it is necessary to improve the current method, or to adopt a new method to obtain the bone repair material.